The present invention relates to systems and components for the protection, control, and/or energy management of electricity distribution systems for electric utility, industrial, manufacturing, commercial, and/or institutional use.
Monitoring of electric parameters, such as current, voltage, energy, power, etc., particularly the measuring and calculating of electric parameters, provides valuable information for power utilities and their customers. Monitoring of electric power is important to ensure that the electric power is effectively and efficiently generated, distributed and utilized. Knowledge about power parameters such as volts, amps, watts, phase relationship between waveforms, KWH, KVAR, KVARH, KVA, KVAH, power factor, frequency, etc., is of foremost concern for utilities and industrial power users. In addition, monitoring of electricity can be used for control and protection purposes.
Typically, electricity from a utility is fed from a primary substation over a distribution cable to several local substations. At the substations, the supply is transformed by distribution transformers from a relatively high voltage on the distributor cable to a lower voltage at which it is supplied to the end consumer. From the substations, the power is provided to industrial users over a distributed power network that supplies power to various loads. Such loads may include, for example, various power machines.
In such arrangements, utilities need to measure power coming out of or into the generating station or going into a power station. It is important to minimize the phase relationship between the current and voltage waveforms of the power being transmitted to minimize losses. It is also important to minimize the amount of harmonics that are present in the voltage and current waveforms. Also, the ability to detect the presence and magnitude of faults in the power system is important. Thus, accurate measurement of these waveforms is important.
In industrial applications, it is important to continuously monitor the voltage, current, phase, harmonics, faults and three phase balance of the power into the machine. These parameters may vary with the machine load. With knowledge of these parameters, the industrial user can better adjust and manage the loads to control machines, determine alarm conditions and/or more efficiently use the power.
Many protection, control, and metering functions in a modern power distribution system require concurrent knowledge of the states of multiple circuits in the system in order to work efficiently and effectively. Examples include differential protection devices and breaker coordination schemes. Conventional devices and systems have addressed these requirements by various coordination and data sharing arrangements. Many of these approaches suffer from cost, performance, reliability, security, and scalability problems.
Accordingly, it is an objective of the present invention to provide a system that overcomes the disadvantages of the prior art by providing a monitoring system that can be used for protection, control, and/or metering of electricity in a electric distribution system.